Etude de la récolte de nourriture par la fourmi polymorphePheidole pallidula dans son milieu naturel

Abstract

The dimorphic ant specicsP. pallidula is widespread in all Mediterranean countries and was the dominant species in our study area. Demographic data such as relative abundance, density, spatial distribution were collected and quantitative observations ofP. pallidula behaviour were made at the time of food exploitation. This allowed us to discern the relations, particularly competitives ones, between their workers and other sympatric ant species (Aphaenogaster senilis, Crematogaster sordidula, Messor barbara, Plagiolepis pygmaea). The ecological success ofP. pallidula seems to depend on 3 main characteristics of its ethology: 1o) its foraging activity both diurnal and nocturnal, 2o) the diversity of its foraging techniques (individual and collective retrievals by minor foragers; short and long lasting foraging trails). 3o) the active participation of majors in intense exploitation of large unretrievable food sources where they could be very efficient to protect food sources from competitors and/or to cut preys' sclcrites. These majors are mainly present on food sources and on trails, exploration of the foraging area being ensured by the minor caste. The adaptive significance of caste polyethism ofP. pallidula species during food exploitation is discussed according to our field data.